I am using EG915U-EU-AB with QuecPython firmware EG915UEUABR03A06M08_OCPU_QPY. I connected a GY-MAX4466 microphone to MIC_P (P88) and MIC_N (P25) on the EVB. Recording starts successfully (returns 0), file is created with data (~28KB), but audio is completely silent (flat line in Audacity). AT+QMIC returns ERROR 58. How do I enable the microphone input path and set mic gain in this QuecPython firmware version?
Dear Customer
Do you mean there is no sound in the recorded audio?
If so, have you exported the file to your PC and checked if there is any audio playback?
Yes, the recorded WAV file has no sound. I exported it to PC and opened in Audacity — completely flat line (digital silence). The file size is correct (~28KB for a few seconds), recording starts and stops without errors, but audio content is zero.
Update after further testing:
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Fixed file size: audio.Record().start() always produces exactly ~28KB regardless of recording duration. Whether I wait 1 second or 30 seconds before calling stop(), the file is always the same size. This suggests it captures a fixed internal buffer rather than continuous audio.
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stream_start() found: After testing signatures, stream_start(PCM, 8000, 0) returns 0 (success). However ring_buf_used() stays at 0 during the entire stream — no data is being captured.
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Microphone hardware confirmed working: Measured 13-29mV AC signal on MIC_P during speech. DC bias on MIC_P is ~0.14V at rest, rising to ~0.35V during speech.
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ring_buf_free() returns garbage: 3,925,868,559 — suggests buffer not properly initialized.
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AT+QMIC returns ERROR 58 on AT port.
Our conclusion: the analog ADC input path is never activated. The stream API runs but samples nothing. Is there a specific initialization call needed to enable the microphone frontend on this firmware? Does this firmware version support analog MIC recording at all?
Dear Customer,
Sorry for the late reply.
I have tested using the attached script and it works fine. Please try it.
audio_Record_play.py (1.4 KB)